Add since linter scoring

[pq]

Adds since linter version info to the scorecard.

A step towards: #1340

/cc @bwilkerson @srawlins

---

Sample run.

name	since	fix	flutter user	flutter repo	pedantic	stagehand	status	bug refs
always_declare_return_types	0.1.4			✅
always_put_control_body_on_new_line	0.1.31			✅
always_put_required_named_parameters_first	0.1.33
always_require_non_null_named_parameters	0.1.31	💡		✅
always_specify_types	0.1.4			✅
annotate_overrides	0.1.11	💡		✅
avoid_annotating_with_dynamic	0.1.31	💡						#1162
avoid_bool_literals_in_conditional_expressions	0.1.46
avoid_types_on_closure_parameters	0.1.31	💡						#1099
avoid_as	0.1.5			✅
avoid_catching_errors	0.1.31
avoid_catches_without_on_clauses	0.1.31
avoid_classes_with_only_static_members	0.1.31			✅
avoid_double_and_int_checks	0.1.47
avoid_empty_else	0.1.8	💡	✅	✅	✅
avoid_field_initializers_in_const_classes	0.1.48			✅
avoid_function_literals_in_foreach_calls	0.1.30			✅
avoid_implementing_value_types	0.1.62
avoid_init_to_null	0.1.11	💡	✅	✅	✅
avoid_js_rounded_ints	0.1.48
avoid_null_checks_in_equality_operators	0.1.31			✅
avoid_positional_boolean_parameters	0.1.31
avoid_private_typedef_functions	0.1.46
avoid_relative_lib_imports	0.1.44			✅	✅
avoid_renaming_method_parameters	0.1.45			✅
avoid_returning_null	0.1.31
avoid_returning_null_for_future	0.1.72
avoid_returning_null_for_void	0.1.69			✅
avoid_return_types_on_setters	0.1.11	💡	✅	✅	✅
avoid_returning_this	0.1.31
avoid_setters_without_getters	0.1.31
avoid_shadowing_type_parameters	0.1.72
avoid_single_cascade_in_expression_statements	0.1.46
avoid_slow_async_io	0.1.30			✅
avoid_types_as_parameter_names	0.1.45			✅	✅
avoid_unused_constructor_parameters	0.1.36			✅
avoid_void_async	0.1.60			✅
await_only_futures	0.1.16	💡	✅	✅
camel_case_types	0.1.1		✅	✅
cancel_subscriptions	0.1.20		✅	✅		✅
cascade_invocations	0.1.29							#1023, #806, #787
close_sinks	0.1.19		✅
comment_references	0.1.17
control_flow_in_finally	0.1.16		✅	✅
constant_identifier_names	0.1.1
curly_braces_in_flow_control_structures	0.1.57
directives_ordering	0.1.30			✅
empty_catches	0.1.22	💡		✅
empty_constructor_bodies	0.1.1	💡	✅	✅
empty_statements	0.1.21	💡	✅	✅
file_names	0.1.54
flutter_style_todos	0.1.61			✅
hash_and_equals	0.1.11		✅	✅		✅
implementation_imports	0.1.4		✅	✅				#1175
invariant_booleans	0.1.25						experimental	#1321, #914, #811, #720, #674
iterable_contains_unrelated_type	0.1.17			✅		✅		#1003
join_return_with_assignment	0.1.31
library_names	0.1.1		✅	✅
library_prefixes	0.1.1			✅
lines_longer_than_80_chars	0.1.56
list_remove_unrelated_type	0.1.22			✅		✅
literal_only_boolean_expressions	0.1.25
no_adjacent_strings_in_list	0.1.30			✅
no_duplicate_case_values	0.1.30			✅	✅
non_constant_identifier_names	0.1.1	💡	✅	✅
null_closures	0.1.56				✅
one_member_abstracts	0.1.1							#990
omit_local_variable_types	0.1.30							#1006
only_throw_errors	0.1.21
overridden_fields	0.1.18			✅
package_api_docs	0.1.1		✅	✅				#213
package_prefixed_library_names	0.1.1		✅	✅
parameter_assignments	0.1.27
prefer_adjacent_string_concatenation	0.1.30			✅				#1191
prefer_bool_in_asserts	0.1.36						deprecated
prefer_collection_literals	0.1.30	💡		✅
prefer_conditional_assignment	0.1.31	💡		✅
prefer_const_constructors	0.1.30			✅
prefer_const_constructors_in_immutables	0.1.33			✅
prefer_const_declarations	0.1.43	💡		✅
prefer_const_literals_to_create_immutables	0.1.43			✅
prefer_asserts_in_initializer_lists	0.1.33			✅
prefer_constructors_over_static_methods	0.1.31
prefer_contains	0.1.30			✅	✅
prefer_equal_for_default_values	0.1.46			✅	✅
prefer_expression_function_bodies	0.1.30
prefer_final_fields	0.1.27	💡		✅
prefer_final_locals	0.1.27	💡		✅				#1342
prefer_foreach	0.1.31			✅
prefer_function_declarations_over_variables	0.1.30
prefer_generic_function_type_aliases	0.1.47			✅
prefer_initializing_formals	0.1.30			✅
prefer_int_literals	0.1.71
prefer_interpolation_to_compose_strings	0.1.30
prefer_iterable_whereType	0.1.47			✅
prefer_is_empty	0.1.30			✅	✅
prefer_is_not_empty	0.1.5	💡	✅	✅	✅			#1232
prefer_mixin	0.1.62
prefer_single_quotes	0.1.33			✅
prefer_typing_uninitialized_variables	0.1.36			✅
prefer_void_to_null	0.1.59			✅
public_member_api_docs	0.1.11
package_names	0.1.31		✅	✅
recursive_getters	0.1.30			✅	✅
slash_for_doc_comments	0.1.1		✅	✅
sort_constructors_first	0.1.11			✅
sort_pub_dependencies	0.1.63			✅
sort_unnamed_constructors_first	0.1.11			✅
super_goes_last	0.1.1		✅	✅
test_types_in_equals	0.1.16		✅	✅		✅		#443
throw_in_finally	0.1.16		✅	✅
type_annotate_public_apis	0.1.5							#1121
type_init_formals	0.1.1	💡	✅	✅
unawaited_futures	0.1.19				✅			#1007, #836, #534, #419
unnecessary_await_in_return	0.1.73
unnecessary_brace_in_string_interps	0.1.30		✅	✅
unnecessary_const	0.1.54			✅
unnecessary_new	0.1.54			✅
unnecessary_null_aware_assignments	0.1.30			✅
unnecessary_null_in_if_null_operators	0.1.30			✅
unnecessary_getters_setters	0.1.1		✅	✅				#275
unnecessary_lambdas	0.1.30	💡
unnecessary_overrides	0.1.31			✅
unnecessary_parenthesis	0.1.44			✅
unnecessary_statements	0.1.36		✅	✅
unnecessary_this	0.1.30	💡		✅
unrelated_type_equality_checks	0.1.16		✅	✅	✅	✅
use_function_type_syntax_for_parameters	0.1.72
use_rethrow_when_possible	0.1.31			✅	✅
use_setters_to_change_properties	0.1.31
use_string_buffers	0.1.31							#777
use_to_and_as_if_applicable	0.1.31
valid_regexps	0.1.22		✅	✅	✅	✅
void_checks	0.1.49

[coveralls]

Coverage remained the same at 96.442% when pulling 38b2e3a on since into 5800aeb on master.